Embodiments of the invention relate to time domain switched inertial sensors (TDSIS). TDSIS provide a way to measure inertial force. Instead of measuring the distance a mass on a spring is displaced by an inertial force, the mass on a spring is intentionally brought into harmonic oscillation, and the time intervals are measured between when the mass passes known fixed locations. The displacement of the entire harmonic oscillation (caused by the inertial force) can then be determined by curve fitting the time intervals into the known time-space relationships of the harmonic oscillator.